Pope Francis marks 12th anniversary in hospital but with his health improving

Pope Francis marked his 12th anniversary as pontiff on Thursday with positive medical updates nearly a month after he was hospitalised with double pneumonia.

In the Vatican's latest medical bulletin on Tuesday, it said a chest X-ray had confirmed improvements just two days after doctors declared that the pope was no longer at imminent risk of death. However, the "general picture remains complex", the bulletin read.

The Holy See has not said how the anniversary of Pope Francis' election as the 266th pontiff might be commemorated. It is a public holiday at the Vatican and masses are planned in his honour at churches in Rome. No medical bulletins will be issued.

Pope Francis on Wednesday remotely followed a Lenten spiritual retreat that has been a mainstay of his papacy. He continues to receive high flows of oxygen through nasal tubes during the day and a non-invasive mechanical mask to aid his rest at night.

Leading papal and political figures in Italy have praised the pontiff this week to mark the anniversary.

"I would like to address a thought of gratitude to the Holy Father for his tireless commitment to peace, dialogue and human dignity," Italian Senate speaker Ignazio La Russa wrote on Facebook.

"His magisterium is a point of reference for millions of people," he added.

Cardinal Michael Czerny, a senior Vatican official, said the pope's anniversary was a "reason for gratitude".

"This year, his illness makes us especially aware (of the anniversary), especially grateful to God, and redoubling our prayers for his full recovery," he said.

Pope Francis has been carrying out some of his duties while in hospital, continuing with ecclesiastical appointments and delivering messages of gratitude to his well-wishers.

The former Cardinal Jorge Mario Bergoglio was elected on the fifth ballot of the 2013 conclave, which was called after Pope Benedict XVI resigned.

While Pope Francis has praised his predecessor's humility in stepping down and said he might follow in his footsteps, more recently he has said the papacy is a job for life.

However, concerns remain over the pontiff's physical frailty, and there has been discussion about the prospect of his resignation even if his health improves further.

Resignation is "a possibility, but it is totally entrusted to the conscience of the Pope," Archbishop Giuseppe Baturi, secretary general of the Italian Bishops' Conference (CEI), told Italian media.